diff --git a/src/tsconfig.strictNullChecks.json b/src/tsconfig.strictNullChecks.json
index 0338a479081b7a8b96e75331e41d741584282808..559ffc69e2def5b679aff1f74f52b941c46b7dc0 100644
--- a/src/tsconfig.strictNullChecks.json
+++ b/src/tsconfig.strictNullChecks.json
@@ -402,6 +402,7 @@
 		"./vs/platform/configuration/common/configurationModels.ts",
 		"./vs/platform/configuration/common/configurationRegistry.ts",
 		"./vs/platform/configuration/node/configuration.ts",
+		"./vs/platform/configuration/node/configurationService.ts",
 		"./vs/platform/configuration/test/common/testConfigurationService.ts",
 		"./vs/platform/contextkey/browser/contextKeyService.ts",
 		"./vs/platform/contextkey/common/contextkey.ts",
diff --git a/src/vs/platform/configuration/node/configurationService.ts b/src/vs/platform/configuration/node/configurationService.ts
index 8073ba694de1f24cacc3d1df88785bd137815d8a..c86f0522dadbb3dd2617778c59128edc5402243a 100644
--- a/src/vs/platform/configuration/node/configurationService.ts
+++ b/src/vs/platform/configuration/node/configurationService.ts
@@ -86,7 +86,7 @@ export class ConfigurationService extends Disposable implements IConfigurationSe
 	}
 
 	reloadConfiguration(folder?: IWorkspaceFolder): Promise<void> {
-		return folder ? Promise.resolve(null) :
+		return folder ? Promise.resolve(void 0) :
 			this.userConfiguration.reload().then(userConfigurationModel => this.onDidChangeUserConfiguration(userConfigurationModel));
 	}